为你解答.
1、我们正在做作业.
肯定句：We are doing our homework.
否定句：We aren't doing our homework.
一般疑问句：Are you doing your homework?
2、他每天都做作业.
肯定句：He does his homework every day.
否定句：He doesn't do his homework every day.
一般疑问句：Does he do his homework every day?
3、老师正在弹钢琴.
肯定句：The teacher is playing the piano.
否定句：The teacher isn't playing the piano.
一般疑问句：Is the teacher playing the piano?
4、他正在干什么?
What is he doing?
5、他经常在周日干什么?
What does he usually do on Sundays?